In portable radio applications, internal radio components contained inside of the radio housing are usually shielded in order to prevent electromagnetic and radio interference (EMI/RFI) from affecting the radio's electronic circuits. This also prevents any radio-generated interference (e.g., microprocessor clock-generated signals) from affecting external electronic devices (e.g., computer equipment located in close proximity to the radio).
It is very difficult and expensive to shield the internal radio electronics when the radio also includes a keyboard and other user controls. Presently, some radios with keyboards use a metal shield with a costly multilayer membrane switch (multilayer flexible circuit) assembly on top of the metal shield to provide shielding and a keypad structure for the radio. This approach not only is very expensive to manufacture, but also increases the chances of keyboard assembly failure. The failures occur when the flexible circuits ("flex") must be folded around the metal shield in order to interconnect to the radio electronics mounted within the radio chassis. A need thus exists for a shielded assembly which can provide for increased reliability and reduced manufacturing cost. The shield assembly must also provide for maximum attenuation of EMI and RFI in order to enhance the operation of the communication device.